Electric boring apparatus



Feb. 4, 1958 R. w. MURRAY 2,822,148 I ELECTRIC BORING APPARATUS Filed Feb. 23. 1954 2 Sheets-Sheet 1 INVENTOR. Robert W. Murray fmza i4 ATTORNEY Feb. 4, 1958 R w MURRAY 2,822,148

ELECTRIC BORING APPARATUS Filed Feb. 23. 1954 2 Sheets-Sheet 2 INVENTOR. Robert W. Murray "57M 4 gzw ATTORNEY ELECTRIC BORING APPARATUS Robert W. Murray, Denver, Colo.

Application February 23, 1954, Serial No. 411,958

4 Claims. (Cl. 255-36) This invention relates to methods and apparatus for flame boring, and more particularly to flame boring with an electric arc, a primary object of the invention being to provide a novel and improved arc-flame boring method and apparatus for drilling a shaft or hole into the earth.

Other objects of the invention are to provide such novel and improved arc-flame boring method and apparatus for drilling a shaft into the earth which: (a) is especially adapted to drill a vertical shaft downwardly to great depths; (b) is adapted to scavenge the drill particles from the shaft as they are avulsed from the bottom of the hole, thereby providing for a continuous boring operation; is operative under water and thereby particularly adapted for use in drilling wells; (d) provides improved means for igniting the arc flame under water as the operation commences and proceeds; (e) is adapted to ream the sidewalls of the shaft during the drilling operation and at the same time to stabilize the sidewalls by congealing loose formations of sand about the shaft; and (f) provides a simple, low-cost method for drilling wells with apparatus which may be constructed as a complete, compact unit adapted to be suspended by a cable, and eliminates the need for large derricks and expensive heavy equipment used in ordinary drilling operations.

With the foregoing, and other objects in view, my invention comprises certain operations and steps, and combinations, constructions and arrangements of parts and elements as hereinafter described, and as defined in the appended claims, and illustrated, in preferred embodiment, in the accompanying drawing, in which: Figure 1 is a vertical section of my arc-flame boring apparatus for drilling a well shaft, a portion of the shaft being indicated; Figure 2 is a plan as viewed from the indicated arrow 2 at Fig. 1; Figure 3 is a section as viewed from the indicated line 3-3 at Fig. 1; Figure 4 is a section as viewed from the indicated line 44 at Fig. 1; Figure 5 is a side elevation of the lower portion of the apparatus positioned the same as in Fig. 1; Figure 6 is a fragmentary sectional detail as viewed from the indicated line 66 at Fig. 5, the broken lines indicating the interrelative movement of parts; Figure 7 is similar to Fig. 6 but with elements removed to show parts otherwise hidden from view; Figlre 8 is a portional side elevation as viewed from the indicated arrow 8 at Fig. 5; Figure 9 is a bottom view of the apparatus; Figure 10 is a bottom view of an alternate construction; Figure 11 is a circuit diagram for an electrode of the apparatus; Figure 12 is a vertical section of another alternate construction; Figure 13 is a fragmentary portion similar to Fig. 6 but with elements included to provide a third alternate construction; and Figure 14 is a fragmentary section as viewed from the indicated line 14-14 at Fig. 6, but enlarged and with elements included to provide a fourth alternate construction.

The art of flame boring into the earth or into a rock face is old, but the applications and uses are restricted and limited. The conventional operation is expensive, using large quantities of oxygen and fuel gas. The prob- 2,822,148 Patented Feb. 4, 1958 lem of scavenging the hole as the boring proceeds becomes almost insurmountable whenever the depth of the hole exceeds a few feet, and practically all flame boring operations are limited to drilling shallow holes or to piercing a vertical rock face with the hole sloping upwardly to permit the waste rock to fiow thence.

However, it is konwn that practically all types of rock will yield in one way or another to intense heat, especially where there is a sudden change of temperature. With such in view, the present invention was conceived and developed, and provides a novel and improved method and apparatus for flame boring into rock.

In essence, the method is to form an are at the rock face which quickly heats that portion of the rock under the arc to an intense temperature. The are is then shifted as by sweeping it about the face of the hole or shaft being bored, whereby the suddenly-applied, extremely-high temperatures cause spalling, melting, or deterioration of the rock. Next, the deteriorated layer may be avulsed from the face of the hole by scraping, by a water jet or by any other suitable means. Finally, the loose particles may be removed from the hole'by air or water flow or any other suitable scavenging means.

My improved flame boring method is particularly adapted for underwater use as in the drilling of a well. The heat of the arc is so intense that it is always within a vapour pocket which is at the rock portion under the are; however, the water keeps the rock portions at each side of the are relatively cool and facilitates a sudden intense temperature change in the various portions of the rock as the arc sweeps about the face of the hole. With such action, the rock will soften or disintegrate either by chemical action brought about by the heat or by the sudden expansion and contraction. With some types of rocks melting will actually occur, even under water, and this melted rock may be lifted from the bottom of the hole, churned in the surrounding water, and comminuated as it solidifies.

The apparatus illustrated in Figs. 1 through 10 of the drawing depicts a flame boring unit adapted to drill a well shaft to any desired depth, operating under water and using water circulating means to facilitate avulsion and scavenging of drill particles. This unit is formed as an elongated body 15, having a rotatable drill head 16 at its base. The body is suspended from a cable 17 and is thereby adapted to be lowered into the shaft S. Power cables 18 and a water feed line 19 are attached to the top of this body and are adapted to be lowered into the shaft alongside the cable 17 for providing the necessary power and water circulation with the unit in operation. It is anticipated that conventional reeling arrangements may be used for holding and lowering the cable and power feed lines into the shaft S and that conventional power generating and water pumping equipment will be stationed at the top of the shaft for operation of the equipment.

The body 15 is formed as an elongated cylindrical case having a diameter necessarily smaller than the diameter of the shaft S to permit a flow of liquid and scavenged particles therepast and a length sufficient to contain necessary actuating elements hereinafter described. The top of this case is enclosed as by a lid 20 having suitable apertures therein for the passage of water and electrical lines, the water line being attached to a shaft-tube 21 which is axially centered in the case to permit rotative elements to be mounted thereon as hereinafter described. The cable 17 is attached to a bail 22 which upstands from the lid 20.

At each end of this case there is provided four wall guides 23, in opposing pairs, which outstand from the case and are shaped as resilient loops to bear against the wall of the shaft S to hold the case in concentric alignment Within the shaft. A pair of axially aligned knife edges 24 upstand from the bearing face of each guide and these edges grip the walls of the shaft to permit vertical axial movement of the case within the shaft but prevent rotation and hold the body against torque causedby rotation of the drill head 16.

Thedrill head 16 is rotated by an electric motor which is carried within the upper portion of the body. The armature 25 of this motor is rotatably mounted about the shaft tube 21 upon bearings 26 at each end of the motor While the field 27 circumscribes the armature and is fixed to the walls of the body in conventional manner. This motor is powered through selected leads 'of the' power cables 18 and structural details and connections are not shown since such are conventional.

The speed of this motor is reduced to rotate the drill head at a selected rate by a series of planetary gears positioned below the motor and upon the shaft tube 21, between the motor and drill head. The lower end of the frame of the armature extends below the lower hearing 26 as a tubular member upon the shaft tube 21 and carries a sun gear 28. This sun gear is surrounded by and meshes with planetary gears 29 which are shafted upon a spider fixed to the body 15. The planetary gears 29, in turn, are surrounded by and mesh with an internal gear 31. The internal gear 31 is formed upon a disc-plate which is rotatably carried upon the shaft tube 21, and includes a tubular portion depending therefrom which carries a second sun gear 28'. Planetary gears 29' surround and mesh with the sun gear and are shafted upon a fixed spider 30'. A second internal gear 31' meshes with and is about the planetary gears. The disc-plate forming the body of the internal gear 31 is mounted upon a shaft 32 which extends downwardly through the body 15 and is attached to the drill head 16.

This drill head shaft 32 is a tubular member and is axially centered in the body 15 upon bearings 33 in axial alignment with the shaft tube 21, the shaft tube telescoping a short distance into the tubular passage of the shaft 32 with a sealing ring 34 between the walls of the shaft tube and shaft 32 passage to prevent leakage from the passage to the interior of the body 15. The shaft 32 is formed as a central member encased within an insulating body which carries electrical leads and commutator elements hereinafter described. This body portion is cylindrical in section within the body 15 and at the opening orifice 35 at the bottom of the body through which the shaft extends, and square or similarly fluted in section in that portion below the body and at the drill head 16, as clearly shown at Fig. 4. A sealing ring 36 is positioned on the orifice 35 about the shaft to prevent leakage of water from the shaft S to the interior of the body 15.

The drill head 16 includes electrodes for arc-flame burning elements and scraper blades and jet orifices for avulsion, scraping and scavenging elements. A transverse row of electrodes 37 is mounted in a box-like container 38 which is affixed to the bottom of the shaft 32 and these electrodes are spaced in the row in any suitable arrangement which will permit them to sweep about and act upon the bottom face of the: shaft as the drill head is rotated. These electrodes may be of any conventional type, but preferably of a type having insulated sides. A uniform arrangement across the bottom of the drill is shown, but a staggered arrangement is also contemplated.

These electrodes are powered from the cables 18 which extend through the body 15 to commutator brushes 39 alongside the shaft 32. The insulated outer body portion of the shaft 32 carries a series of commutator rings 40, which are contacted by the brushes 39. A series of leads 41 extend from the rings 40, through the insulated portion of shaft. 32' and to the electrodes 37. It is to be noted that the operation of holding a hot are against a rock face requires very high voltages, and that the outer electrodes which sweep about the edge of the shaft may require considerably more voltage than the electrodes at the center whichr'em'ain relatively stationary; hence individual leads may be required for selected groups of electrodes or for individual electrodes. It is to be understood that the power generating equipment used in conjunction with the apparatus will include suitable voltage regulating means to take care of this need.

The scraper blades 42 are 'inounted upon a head 43 which is slidable upon the fluted section of the shaft 32 and is normally held in a downwardly extended position by a spring 44 to abut against'a lip 45 at the bottom of the shaft. The scraper blades extend outwardly from each side'of "the head '43 at right angles to the row of electrodes as clearly illustrated at Fig. 9 or they may be otherwise angled to more closely follow the electrodes as illustrated at Fig. 10. This latter construction is especially desirable when the proporties of the rock are such that it melts instead of spells. The lip of these blades may be straight as shown, or may be serrated or otherwise formed.

In operation of the unit, the drill head 16 is lowered against the bottom of the shaft with the scraper blades contacting the bottom first, then the electrodes are lowered to operaive position with the scraper blades and head moving upwardly on the shaft 32. As the electrodes burn away, the container 38 carrying them is lowered with respect to the blades and the spacing of the electrodes with the bottom of the shaft.

The scraper blades pile up loose drill particles as they rotate about the bottom of the shaft. To remove and scavenge such particles from the hole there is a plurality of orifices 46 in the face of each blade which are directed upwardly and provide for the formation of upwardly directed water jets which move particles piled against the blades upwardly and out of the shaft. The orifices of each blade are joined to a manifold 47, which is connected by a lead 48 to passages 49 (Fig. 7) in the head 43. The passage within the shaft 32 bifurcates near the bottom to provide leads 50 (Fig. 6) which register with the passages 49 in the head, each passage 49 terminating at the inner face of the head as axially slotted openings which provide continuous registration with movement of the head upon the shaft.

The heat of an arc under water results in a vapor pocket about the electrode. To increase the extent of such vapor pocket and to facilitate the heating action of the arc, the head 43 carries a hood 51 which overcov'e'rs the container 38 and the electrodes 37 depending froir'i it. The hood 51 is connected to the scraper blades and is thereby adapted to move upwardly with the scraper blades 42 as the electrodes burn away. This provides for a regular space' between the lower edge of the hood and the bottom of the shaft which may be such that only asma ll amount of water need be blown away from the electrodes as the arcs form. In the alternate construction shown at Fig. 14 the hood 51 has a flexible strip 51a of heat resist ing material around its lower edge which tends to hold all water out of the space underneath the hood when the arcs areburning and forming Vapor pressure. It is to be noted that the edges of this strip 51a will innate the lower edge of the hood in a direction to trail themovement of the hood as indicated by the arrow A atl ig. 14.

An electrode 37' outstands from each side of the hood 51 to provide for an are against the' cylindrical sidewall of the shaft and serves to ream the hole. Although not shown, it is to be noted that a scraper may be positioned alongside this electrode to remove particles from the sidewall of the shaft which are loosened by the heat of the are.

This electrode 37' not only serves to disintegrate hard formations of rock, but the'heat will also congeal certain loose formations of sand and strengthen the walls of the shaft as the drilling proceeds and thereby eliminate the need for easing. In conventional drilling operations certain' substances are used in the circulating water, such as bentonite, which are particularly well adapted for congealing under the action of heat and it is anticipated that with the present apparatus .he water may contain congealants which act to cement a film upon the sidewalls of the shaft under the action of heat. The alternate construction shown at Fig. 13 provides for a supplemental water passage 49a which forms a tube directed to discharge adjacent to the electrode 37' against the wall of the shaft S. This supplemental passage 4% may be interconnected with the regular water supply or to a special water supply furnished by suitable passageways through the apparatus which are not herein shown, such special passageways may be used for supplying fluid with congealants for discharge through the supplemental passage 490.

It is to be noted that the scraper elements do not extend to the center of the drill head 16 because of the construction of the hood, however, such is not critical since this center portion of the shaft bottom is subjected to more continuous and intense heating than the outer portion of the shaft bottom, and the movement of water into this portion will be sufficiently turbulent to loosen and Wash away the drill particles. A water jet may be directed to the center of the hole to facilitate such action.

My improved electrical circuit is shown at Fig. 11, and is adapted to permit an arc to form at an electrode with the ground surface. The main circuit includes a cable 18 and lead 41 which are interconnected at the commutator 40. The electrode 37 is at the end of the lead 41 and a generator 52 is at the end of the cable 18. The generator is grounded, and the circuit is completed whenever arcing occurs at the electrode. A supplementary circuit is superposed upon the first to facilitate arcing at the electrode. This circuit comprises a lead 53 which is connected with the cable 18, the cable 18 and the lead 41, the electrode 37 at the end of the lead 41 and a pulsator 54 and high voltage supply transformer 55 at the end of the lead 53. The pulsator is adapted to intermittently open and close the circuit, and when closed sparking occurs between the electrode and ground.

To prevent a high voltage impulse from grounding out through the generator 52, a choke coil 56 is interposed in the cable 18 between the supplementary circuit connection and the generator. To avoid a reversal of current into the transformer 55, a condenser 57 is interposed in the lead 53.

In operation, the series of sparks at the electrode from the high voltage circuit ionizes the path between the electrode and ground permitting a permanent arc to form, and such reignites the arc at any time it is accidentally put out as by the action of the water or the like. Pure water is of comparatively high resistance, and to facilitate ioni Zation within the water a small amount of salt of electrolyte may be added to the circulating water. Such a salt can also increase the conductivity into the rock by forming salt deposits on the surface as the vapor pocket moves over the wet rock.

The unit illustrated at Fig. 12 is a modified form of apparatus wherein the drill head 16a is attached to a rotary stem which may extend upwards to the surface of the well shaft as does a conventional rotary drill stem. The stem 58 is hollow for the circulation of water and is formed to provide an electrical lead 18a within it by any suitable connection at the various joints of the stem. The electrode is a single transverse bar 37:: aflixed to the bottom of the drill head and is adapted to cause arcing at the high points of the bottom of the shaft. The are will shift across the bar 37a always to the portion of the bottom of the shaft which is highest and the closest to the bar 37a. In this unit the scraper arms are similar in construction as hereinbefore described, but need not be mounted upon a shif table head since the wear on the electrodes will be relatively slight.

In operation, the unit is lowered into the shaft, the drill head rotated and a further gradual lowering commenced until the scraper blades contact the bottom of the shaft. Then arcing commences, initiated by the high voltage supplementary circuit. As soon as the heavy current from the generator 52 commences to deteriorate the rock, the scraper loosens it and the water flow removes it from the shaft.

It is to be noted that various alternate constructions are possible without departing from the spirit of my invention. For instance, the electric motor within the body 15 may be replaced by a motor run by the action of the circulating water. It is obvious that others skilled in the art can devise alternate and equivalent constructions which are within the scope and spirit of my invention, hence it is my desire that my protection be limited only by the proper scope of the appended claims.

I claim:

1. Electric-arc boring apparatus adapted to bore a vertical shaft into rock, including, in combination, a body including a rotatable drill head at its bottom adapted to be lowered into the shaft, electrodes depending below the head, current means adapted to form an arc between the electrodes and shaft bottom with the electrodes close to the shaft bottom, means adapted to rotate the drill head and thereby sweep the arcs about the bottom of the shaft to act upon the rock therebelow, means for avulsing and scavenging rock particles from the shaft bottom and a hood over the electrodes to provide a vapor pocket at the electrodes with the electrodes arcing under water.

2. The apparatus defined in claim 1, wherein the lower edges of the hood are extended downwardly by a strip of flexible, heat-resisting material.

3. Electric-arc boring apparatus adapted to bore a vertical shaft into rock, including, in combination, a body having a rotatable drill head at its bottom adapted to be lowered into the shaft, electrodes depending below the head, an electrode at the side of the head, current means adapted to form an are between the electrodes and the shaft bottom and sidewall with the electrodes close to the shaft bottom, means adapted to rotate the drill head and thereby sweep the arcs about the bottom of the shaft to act upon the rock therebelow and to sweep the are at the sidewall about the sidewall to act upon the rock at the sidewall and thereby perform a reaming operation to the sidewall of the shaft, and means for avulsing and scavenging rock particles from the shaft bottom and sidewall.

4. The apparatus defined in claim 3, including a fluid passageway to the drill head terminating as an orifice alongside the electrode at the side of the head and adapted to permit fluid flowing therethrough to form a jet directed against the wall of the shaft.

References Cited in the file of this patent UNITED STATES PATENTS 

